SUMMARY 


Functional genomic programs in agronomic species or their wild relatives will not only lead 
to important advances in general knowledge, but present also a qualitative leap in the field of 
plant breeding. In particular, the use of genomic tools will help to overcome two of the 
challenges that still remain in the field of molecular breeding (ie, via transformation): the 
identification of genes that actually control the agronomic characters and detection of signals 
regulation mechanisms that modulate the spatiotemporal expression of transgenes, avoiding 
the energy waste generated by the use of constitutive promoters (eg, 35S) and the pleiotropic 
effects that usually are caused. Among the possibilities to achieve these objectives, insertional 
mutagenesis by T-DNA highlights, because has become in recent years a basic tool for the 
identification and tagging of genes, and for analysing their function. Indeed, the disruption of 
an endogenous gene or the T-DNA insertion in its vicinity can cause the disruption or 
alteration of its function, providing valuable information about the role of a gene in a given 
character. Other application of insertional mutagenesis by T-DNA is the detection of 
regulatory elements using the so-called "trapping” system. It is a system of indentifying genes 
on the basis of the expression pattern of a reporter gene that is randomly integrated into the 
genome. The reporter gene is expressed in a fashion that mimics the normal expression 
pattern of a gene at the insertion site. The most relevant of these approaches is that the 
disrupted gene is tagged by the T-DNA, which facilitates its cloning. 

In our laboratory we are working on a project in collaboration with the groups of Drs. Rafael 
Lozano and Trinidad Angosto (University of Almería) and Dr. M ª Carmen Bolarín (CEBAS, 
CSIC, Murcia) in which we are using two genomic tools (insertional mutagenesis and 
trapping) in tomato (cvs. P73 and Moneymaker) and a related wild species (Solanum 
pennellii) to identify coding sequences or regulatory elements of genes involved in processes 
of vegetative development (plant architecture) and reproductive development (flower and 
fruit) as well as two types of abiotic stress (salinity and hydric stress ). 

The present doctoral thesis contributes to this research project by the generation of a 
collection of T-DNA insertion lines in tomato and the identification of mutants affected in 
characters related to development. In particular 1200 T-DNA lines were generated and for 
most of them the descendent TG2 has been obtained. The characterization of these lines TG1 
has led to the detection of 255 mutants (dominant, semidominant or additive type) affected in 
vegetative and/or reproductive characters. In addition, TG2 progenies (specifically 37) have 
been characterized which has allowed the identification of 6 recessive mutants. Moreover, the 
use of the enhancer trap to generate lines of T-DNA has permitted to identify genotypes with 
interesting expression patterns.